We study/are studying Algebra this semester.
are studying
study
Leo saves/is saving his money to buy trainers.
saves
is saving
Sam's two so he doesn't go/ isn't going to school.
isn't go
doesn't go
You don't watch/ aren't watching this. Can I change the channel?
aren't watching
don't watch
How often do you play/ are you playing video games?
do you play
are you playing